JP2022553752A - Small laser steering end effector - Google Patents

Abstract

A miniature laser steering end effector includes a frame, at least two active mirrors, and a pair of actuators. The frame has a maximum dimension in a plane orthogonal to the longitudinal axis of 13 mm or less, and the mirror is mounted near the distal end of the frame. The actuators are attached to the frame and configured to each change the tilt of the active mirror with respect to the frame. A path is provided through the frame for directing the laser beam to the mirrors, and the mirrors are positionable and configurable via actuators to reflect the laser beam from each mirror toward an external target. [Selection drawing] Fig. 4

Description

The background statements that follow may reflect hindsight gained from the disclosed invention and are not necessarily admitted to be prior art for these features.

More than 30,000 people in the United States were diagnosed with pharyngeal or laryngeal cancer in 2018, and 6,000 died. These cancers have a significant negative impact on quality of life, symptoms such as dysphagia and dysphonia often lead to depression and social isolation, and curative treatments rarely exacerbate these functional disorders. No. The morbidity has historically been caused by tobacco smoking but more recently by human papillomavirus, resulting in a historically younger patient population with serious concerns over long-term functional outcomes. .

Therefore, there is a strong demand for therapeutic methods that can maintain organ function after treatment of these cancers. Partial or total organ removal by open surgery is extreme and almost guarantees excellent oncological results, but at the expense of functional results. Non-surgical methods, including induction chemotherapy, intensity-modulated radiation therapy, and concurrent chemotherapy with radiation therapy, have achieved good oncological outcomes while yielding functional results superior to open surgery. be done. Such methods are now recommended for most laryngeal cancers. Over the past two decades, however, long-term morbidity and disability associated with radiation therapy has caused otolaryngologists to reconsider surgery. In particular, minimally invasive surgery is of interest from the viewpoint of preserving more healthy tissue and improving postoperative organ function compared to open surgery.

Transoral laser microsurgery (TLM) is the most mature minimally invasive approach. In TLM, a carbon dioxide laser is coupled to an operating microscope and delivered through a laryngoscope that provides line-of-sight access to the upper respiratory tract. The operator uses manual tools inserted through the laryngoscope to retract the lesion and uses the microscope's micromanipulators to manipulate the laser beam and excise the diseased tissue. Advanced systems motorize the micromanipulator, allowing the surgeon to direct the laser along a predetermined arc or line at a precisely controlled speed, resulting in very high quality incisions. The most important limitation of TLM is the line-of-sight constraint, which limits both vision and illumination. Additionally, the long and narrow laryngoscope makes manual manipulation of the tools required for retraction and suturing difficult.

To address these shortcomings, Transoral Robotic Surgery (TORS) was developed in the mid-2000s. In TORS, a flexible or articulated robotic manipulator is used in combination with an endoscopic vision system to provide excellent visualization of the surgical site and tissue manipulation. Currently in clinical use are the DA VINCI multiport system and the DA VINCI single port system (Intuitive Surgical Inc., Sunnyvale, CA) and the FLEX robotic system (Medrobotics, Raynham, MA, USA).

However, compared to TLM, TORS is resected with an electric scalpel, which has the drawback of causing stronger postoperative pain and taking longer to recover than similar surgery performed with TLM. In recent years, the development of hollow-core fibers that can be irradiated with carbon dioxide lasers in flexible devices is expected to alleviate this problem to some extent and increase the use of lasers in TORS. However, because fiber-based lasers are held and manipulated by robotic tools, they lack the spatial repeatability, accuracy, and speed of free-beam scanning systems. This means that the incision quality is reduced compared to the free beam system used for TLM. Free beam systems have the added benefit of keeping the surgical site clear and visualizing exposure and margins.

A number of prototype endoscopic devices have been developed for minimally invasive laser scanning tasks, each taking a different approach to a difficult design challenge. In "Endoscopic laser scalpel for head and neck cancer surgery" by S. Patel et al., Photonic Therapeutics and Diagnostics VIII, Vol. 8207, International Society for Optics and Photonics 82071S (2012), a DC motor-driven Risley ) using a prism, which allows for an easy-to-implement control scheme, but the scanning speed is very limited (2 Hz). In O. Ferhanoglu et al., "A 5-mm piezo-scanning fiber device for high speed ultrafast laser microsurgery," Biomedical Optics Express, Vol. The fiber is directly bent to achieve a wide bandwidth (1 kHz) with a thin device profile (5 mm diameter). However, it results in a reduced field of view (200×200 μm). A. Acemoglu et al., "Design and control of a magnetic laser scanner for endoscopic microsurgeries," IEEE/ASME Transactions on Mechatronics (2019) used electromagnets to bend the fiber and expand the range of motion to 3 × 3 mm. Doing so sacrifices bandwidth (15 Hz). Finally, in R. Renevier et al., "Endoscopic laser surgery: design, modeling and control," IEEE/ASME Transactions on Mechatronics, Vol. 22, No. 1, 99-106 (2017), the FEMTO-ST laboratory We describe the development of a system to articulate a silicon mirror held on a tip-tilt stage using an off-the-shelf piezoelectric linear actuator, which achieves a 20 × 20 mm field of view at a low scan rate (17 Hz). ing.

SUMMARY OF THE INVENTION A compact laser steering end effector and a method of using the end effector particularly for surgery are described herein, and various embodiments of the apparatus and methods incorporate the elements, features and steps described below. may include some or all.

A miniature laser steering end effector includes a frame, at least two active mirrors, and a pair of actuators. The frame has a maximum dimension in a plane perpendicular to the longitudinal axis of the frame of 13 mm or less, and the mirror is positioned closer to the distal end of the frame (i.e., closer to the distal end than to the proximal end of the frame). It is attached. The actuators are attached to the frame and configured to each change the tilt of the active mirror with respect to the frame. A path is provided through the frame to deliver the laser beam to the mirrors, which are orientable and configurable via actuators to reflect the laser beam from each mirror on its way to the external target.

In the method of robotic laser steering, a laser beam is generated and directed at the proximal end of the end effector to a region near the distal end of the end effector. The laser beam is reflected off at least two active mirrors in a region near the distal end of the end effector, and an actuator is used to change the tilt direction of the at least two active mirrors to move the laser beam across the target. .

The apparatus and methods described herein can incorporate the advantages of both TLM and TORS in a laser scanning system operating at the tip of a robotic manipulator. The apparatus and method may allow for more precise incisions and correspondingly less tissue damage than existing laser or electrocautery tools. Furthermore, making the laser fiber move within a robotic manipulator can relax constraints on fiber design and use, making currently available _CO2 laser fibers expensive (approximately US$1,000) and single-use. It is advantageous to consider one thing. A prototype device for realizing this TLM/TORS hybrid paradigm is described below.

Although minimally invasive surgical techniques have emerged in recent years that can preserve more healthy tissue, they are still limited in important ways. Here, the existing major advantages of (a) the high-quality incision and post-operative pain reduction achievable with oral laser microsurgery and (b) the superior visualization and tissue manipulation offered by oral robotic surgery are discussed. We describe a device that can combine the two advantages of a minimally invasive approach. In a specific example, an 11 mm diameter device is connected to a fiber optic laser source and delivers a focused laser beam on a plane of 18 x 10 mm on a controllable trajectory with a velocity of up to 7 m/s.

By combining the strengths of TORS and TLM, this approach is expected to improve the quality of treatment of cancers such as pharyngeal and laryngeal cancers. This provides better access and exposure than TLM alone, and better quality of cut than TORS alone. As a result, the operator's procedure is streamlined and the patient's functional outcome is improved. Among other applications, this approach can be used for laser-assisted cardiac ablation, laser-assisted gastrointestinal surgery, laser-assisted abdominal surgery, laser-assisted transnasocranial base surgery, and the like.

The end effectors described herein can be operated with high speed and precision, enabling important new ways of robotic interaction with living tissue. In particular, end effectors can be incorporated into microrobotic devices to provide sophisticated control of laser energy in minimally invasive surgery. The high-bandwidth distal actuation provided by these devices and methods can be integrated with existing surgical tools to precisely control the position of fiber-delivered lasers. The manufacturing and modular assembly approach described herein can create a significantly smaller device with higher bandwidth than the current state of the art while achieving a range of motion similar to existing tools. For example, the device can be 6 mm or less in diameter and 16 mm or less in length, and can be used over a wide range (e.g., ±10° on both two axes) with excellent static repeatability (e.g., ±200 μm). A fiber-delivered laser bean can be focused and steered at high speed (eg, 1.2 kHz bandwidth). This approach allows precise control over a wide range of laser velocity, or energy delivery time, and thus provides greater control of surgical energy delivery than existing rigid cable-driven tools. Such a dexterous energy delivery approach can be deployed in a wide variety of surgical areas where controllable energy is required in confined spaces.

FIG. 1 shows a first embodiment of an end effector 10 of a laser scanning system for use in oral robotic surgery. An end effector 10 receives fiber input and manipulates the focal spot on the surgical plane. FIG. 2 is a long exposure photograph showing a typical cut profile used in laser-based tissue ablation using the end effector design of FIG. FIG. 3 is a long exposure photograph showing a typical cut profile used in laser-based tissue ablation using the end effector design of FIG. FIG. 4 is a perspective view of a second embodiment of a miniature laser steering end effector 10 for robotic surgery. FIG. 5 is an end view of the miniature laser steering end effector 10 for robotic surgery shown in FIG. FIG. 6 is a side view of the miniature laser steering end effector 10 for robotic surgery shown in FIGS. FIG. 7 is a perspective view of the miniature laser steering end effector 10 for robotic surgery shown in FIGS. FIG. 8 is a perspective view of a first embodiment of laser scanning end effector 10 defining the location of the major subsystems. FIG. 9 shows the optical subsystem 48 of the end effector 10 of FIG. An optical subsystem 48 connects the fiber optic light source to the laser scanner. FIG. 10 shows the actuation subsystem 50 of the end effector 10 of FIG. 8, which includes piezoelectric bending actuators 18 and 22 and a rigid mechanical frame (base) 40 that aligns the optics with the rest of the device. including. FIG. 11 shows mirror subsystem 52 of end effector 10, including motion transfer linkage 38 and flat active mirror 28/30. FIG. 12 shows the transmitted motion of the crank slider represented schematically by selecting the design values shown in the table. FIG. 13 is a view of the crank-slider arm on the fabricated linkage of the first embodiment of the end effector. 13 shows the first mirror linkage 38. FIG. A first set of solid lines 71 indicates the effective links of the crank sliders, dotted lines 73 represent the axis of rotation of the crank, and a second set of solid lines 75 are bent rearwardly to facilitate assembly of the linkage 38. physical part. The joints are represented by black circles 77 and the translation of the slider and the rotation of the crank are represented by dashed black trajectories 79 . FIG. 14 is a view of the crank-slider arm on the fabricated linkage of the first embodiment of the end effector. FIG. 14 shows the second mirror linkage 38. FIG. A first set of solid lines 71 indicates the effective links of the crank sliders, dotted lines 73 represent the axis of rotation of the crank, and a second set of solid lines 75 are bent rearwardly to facilitate assembly of the linkage 38. physical part. The joints are represented by black circles 77 and the translation of the slider and the rotation of the crank are represented by dashed black trajectories 79 . FIG. 15 is a schematic diagram of a laser scanning system with key symbols defined. It is a figure which shows a linkage manufacturing process. FIG. 16 shows individual layers of rigid material 60, flexible material 62, and adhesive 64 cut using laser micromachining. It is a figure which shows a linkage manufacturing process. FIG. 17 shows layers 60, 62 aligned on pins 68 and laminated using heat and pressure 66 of lamination plates. It is a figure which shows a linkage manufacturing process. In FIG. 18, further laser micromachining has produced the structure of the linkage 38 of the first embodiment of the end effector. It is a figure which shows a linkage manufacturing process. In FIG. 19, linkage structure 38 is partially deployed after releasing the assembly tabs. It is a figure which shows a linkage manufacturing process. In FIG. 20, a 3D printed assembly jig 70 is used to bend the linkage arm to the desired position. It is a figure which shows a linkage manufacturing process. In FIG. 21, the last tab is released and linkage 38 is ready to merge with the rest of the device. FIG. 22 plots the measured mirror angle as a function of actuator voltage for the first mirror 28'' and the second mirror 30'' of the first embodiment of the end effector. The overall trend is well captured by the theoretical model first and second mirrors 28' and 30', with average absolute errors of 0.6° and 1.2° for the first and second mirrors, respectively. be. FIG. 23 plots the frequency response of the actuator-transmission-mirror subsystems of the first linkage actuator 18 and the second linkage actuator 22 of the first embodiment of the end effector. FIG. 24 shows the laser spot position tracking setup for the first embodiment of the end effector as viewed with a high speed camera. The theoretical field of view 72 and the achieved field of view 74 from a standoff distance of 20 mm are shown. FIG. 25 shows shapes drawn at different velocities using the first embodiment of the end effector, demonstrating the open loop trajectory tracking capability of the laser scanner. The high speed performance of the system is demonstrated through repeatability over various commanded speeds. FIG. 26 shows a three mirror angle configuration of a three mirror galvanometer. FIG. 27 shows a two mirror angle configuration of a two mirror galvanometer. FIG. 28 shows two additional mirror angle configurations for a two-mirror galvanometer. FIG. 29 shows the first active mirror 28 and associated actuator 18 and passive transfer linkage 38 of the second embodiment of the end effector. FIG. 30 shows the second active mirror 30 and associated actuator 22 and passive transfer linkage 38 of the second embodiment of the end effector. Figure 31 shows the modular components of a second embodiment of a laser steering end effector. FIG. 32 is a plot of the frequency response of the first and second mirrors of the second embodiment of the end effector in terms of phase and amplitude, respectively. FIG. 33 is a plot of the frequency response of the first and second mirrors of the second embodiment of the end effector in terms of phase and amplitude, respectively. FIG. 34 is an image produced by the high speed motion of the laser steering system of the second embodiment of the end effector. FIG. 35 shows how the high speed image (generated at 3,900 mm/sec) closely matches the trajectory generated at low speed (7.8 mm/sec) by the laser system of the second embodiment of the end effector. show.

In the accompanying drawings, like reference characters refer to the same or similar parts throughout the different views. The drawings are not necessarily to scale, emphasis rather being placed on illustrating certain principles described below. For drawings containing text (words, reference letters, and/or numbers), alternative versions of the drawings without such text are to be understood as being part of this disclosure and are to be understood as part of the present disclosure. Alternate drawings may be used instead.

These and other features and advantages of various aspects of the invention will become apparent from the following detailed description of various concepts and specific embodiments within the broad scope of the invention. The various aspects of the subject matter introduced above and discussed in more detail below can be implemented in any of a number of ways, and the subject matter is not limited to any particular implementation. Specific implementations and application examples are provided primarily for illustrative purposes.

Unless otherwise defined, used, or characterized herein, the terms (including technical and scientific terms) used herein have meanings consistent with their accepted meanings in the context of the relevant art. and not in an idealized or overly formal sense unless explicitly defined. For example, when referring to a particular composition, that composition may be substantially (but not completely) pure, but practical imperfection realities may apply. For example, the potential presence of at least trace amounts of impurities (eg, less than 1 or 2%) can be understood to be within the scope of the description. Similarly, when a particular shape is referred to, that shape is intended to include imperfect variations from the ideal shape, eg, due to manufacturing tolerances. Percentages or concentrations expressed herein may be by weight or by volume. Unless otherwise specified, the processes, procedures, and phenomena described below employ atmospheric pressure (ie, for example, about 50-120 kPa, about 90-110 kPa, etc.) and temperature (ie, for example, −20-50° C., about 10-35° C.). °C).

Although the terms first, second, third, etc. are used herein to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another. Thus, a first element discussed below could also be termed a second element without departing from the teachings of the exemplary embodiments.

Spatially relative terms such as "top", "bottom", "left", "right", "front", "back" are used herein for ease of explanation as shown in the figures. may be used in writing to describe the relationship of one element to another. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations described and illustrated herein, as well as the configurations illustrated. It should be understood that there are For example, if the apparatus in the figures were reversed, an element described as "below" or "beneath" another element or feature would be oriented "above" that other element or feature. be. Thus, the exemplary term "top" can encompass both an orientation of up and down. The device may be oriented in other ways (eg, rotated 90 degrees or at other orientations), and the spatially relative statements used herein may be interpreted accordingly. The term "about" can mean within ±10% of the stated value. Further, when a range of values is provided, each subrange and each individual value between the upper and lower limits of the range is contemplated and thus disclosed.

Further, in this disclosure, when an element is referred to as “on,” “connected,” “coupled,” “in contact with,” etc. another element, the other element is directly attached to the other element unless otherwise stated. It may be overlying, connected, coupled, touching, or there may be intervening elements.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of example embodiments. As used herein, singular forms such as those introduced by the articles "a" and "an" are intended to include plural forms as well, unless the context indicates otherwise. Additionally, the terms “comprising,” “contains,” “comprising,” and “comprising” specify the presence of a recited element or step but not one or more other elements or steps. does not preclude its presence or addition.

Additionally, the various components identified herein may be provided in a fully assembled form. or sold as a kit containing instructions (e.g., in written, video, or audio format) for the customer to assemble and/or modify some or all of the components together to create a finished product; can do.

Minimally invasive surgery allows access to internal anatomy through natural orifices or small external incisions. This includes interventions as diverse as catheter delivery of stents (angioplasty), flexible endoscopy of the gastrointestinal tract, laparoscopic treatment of abdominal disease, and transnasal skull base surgery for neurological disease. Common to many of these surgeries is the need for a wrist joint at the distal end of the tool to manipulate tissue and visualize the surgical site. The need for this joint has been an important motivation for the introduction of robotics into minimally invasive surgery, and is still an active area of research and development.

Proximal actuation cable transmission approaches are superior to achieve wrist joint motion due to the significant size constraints imposed by the access method and anatomical size. However, the drawbacks of cable drives are well known: power output is limited by the cable's allowable strain, and bandwidth is limited by the series elasticity and the mass and elasticity of the anti-backlash preload component. These constraints have motivated significant research efforts to develop novel distal organ mechanisms actuated by other means, such as shape memory actuators, pneumatic fluids, and flexible rods, that achieve dexterity without the constraints of cable actuation. rice field.

This document focuses on a subset of instruments used in minimally invasive surgery, specifically tools used for energy delivery. Common surgical energy sources include monopolar and bipolar radiofrequency currents (electrosurgery), thermal ablation (direct current heating), ultrasonic vibrations, argon beam coagulation (argon helps conduct radiofrequency currents), and lasers. is included. These tools enable cutting, coagulation, desiccation, and charring of tissue deep within the body and are therefore essential to the surgical workflow. These different energy sources end up with the same effect of denaturing proteins by heating the tissue. Moreover, these energy sources are now being used in similar ways. Specifically, the energy source is brought close to the tissue (eg, within a few millimeters) and energy is delivered directly from the electrode or fiber to the anatomy being treated.

However, more sophisticated approaches are possible for the delivery of laser energy. Although current laser-based instruments are used in a static, close-contact manner, a dynamic approach using a miniature laser galvanometer as the wrist for manipulating laser energy can also be employed. Because the laser can be focused and steered using low-inertia optics, high-bandwidth distal actuation can be used to control the laser's position. This provides the same advantages that a robotic wrist gives a mechanical end effector (i.e. the ability to maneuver around corners and obstacles), while precisely controlling the laser velocity onto the tissue over a wide range. to achieve additional functionality. This is important because the laser velocity strongly affects the duration of laser irradiation, and is a key factor in determining the quality of laser-tissue interaction, such as incision depth, extent of thermal damage, and hemostatic effect.

A challenge in creating this type of robotic device is the required optical, electrical, and mechanical complexity for a small package. Device diameter is an important constraint and depends on the type of surgical instrument used. Examples of commonly used tools range in size: Colonoscopes 9.7-14.8 mm (such as PCF-PH190I/L and CF-FH260AZI/L from Olympus Medical Systems), laparoscopic tools is 5-8 mm (such as Intuitive Surgical's da VinciSP), 2.6-4.9 mm for nasal access rhinoscopy (such as Olympus Medical Systems' ENF-V3 and ENF-VT3 rhinoscopy), and 2.67 for cardiac catheters. ~3.33 mm (such as Biosense Webster's AcuNav catheter).

Using breakthroughs in millimeter-scale design and manufacturing, we demonstrate how microrobotic laser beam steering can be integrated with a subset of these tools. Our approach builds on recent advances in robotics and medicine, leveraging millimeter-scale actuators and sensors for more precise control of tools and manipulation of tissue. This laser steering solution example is 6 mm in diameter and therefore seamlessly integrates into existing workflows for flexible gastrointestinal and single-injection laparoscopic surgery. Conventional tools were difficult to adapt to this setting, and lasers were particularly important.

End effectors with microrobotic laser beam steering can be integrated with surgical instruments such as colonoscopes (Olympus CF-100L). The end effector can be attached externally to the surgical instrument or small enough to be internally integrated into a special purpose flexible scope. The device is 16 mm long and has the ability to steer a focused laser beam over ±10° on two orthogonal axes with a mechanical bandwidth of 1.2 kHz.

The performance achieved represents a significant improvement over current technology, which tends to be bulky and slow. All of these solutions are greater than 1 centimeter in diameter and greater than 2 centimeters in length. These devices achieve a range of motion similar to ours, but at the cost of speed due to the actuators and their mechanics. In contrast, our approach uses piezoelectric bending actuators operating through bending-type transmissions to generate rotational motion of low-inertia mirrors. This allows for mechanical bandwidths one to two orders of magnitude greater than current technology and excellent reproducibility (ie accuracy).

Here, we describe significant advances in design, manufacturing, and control that allow us to exceed the performance of state-of-the-art devices. These include general principles for constructing miniature laser galvanometers and specific design details of the device. Our approach is to divide the device into modules (lenses, actuators, mirrors, etc.), validate each one individually, mount them to the disk, and assemble them into a railed superstructure that serves as a common mechanical ground, thus creating an assembly of parts. Minimize the number of parts and facilitate the adjustment of critical parts. In terms of manufacturing, lamination techniques can be used to create compact compliant mechanisms that can produce large angles of mirror rotation without sacrificing compactness. On the control side, a low order hysteresis correction scheme can be used to correct the hysteresis of the piezoelectric bending actuators and intermediate mechanisms.

A laser scanning system including a miniature laser steering end effector 10 for use in oral robotic surgery is shown in FIG. This device receives laser input from an optical fiber 12 and steers a focused spot on the surgical surface. The device includes two low-power navigation lasers that illuminate the internal cavity to aid in visualization and navigating the end effector to its desired location, and a high-power surgical laser to cut tissue. It may contain a laser. The laser passes from the optical fiber 12 through the collimator 14 to the mechanical structure 16 which passes through a first linkage actuator 18 configured to displace a first link and mirror assembly 20 and a second link and mirror assembly. and a second linkage actuator 22 configured to displace the mirror assembly 24 . Figures 2 and 3 are long exposure photographs showing typical cut profiles used in laser-based tissue ablation.

As shown in Figures 4 to 11, the recently developed microfabrication technology P. S. Sreetharan et al., "Monolithic fabrication of millimeter-scale machines", Journal of Micromechanics and Microengineering, Vol. 22, No. 5, 055027 (2012) is used. can be used to create a miniature mechanical passive transfer linkage 38 that directs the quasi-linear motion of high bandwidth piezoelectric bending actuators 18 and 22 to mirrors 28 and 30 that receive the laser beam after beam reflection from fixed mirror 42 . into a rotational motion that is used to orient the In this example device, two such actuator-transmission-mirror combinations are arranged orthogonally such that the two actuation inputs from actuators 18 and 22 correspond to orthogonal ablation of the target tissue. include. The light is transmitted to the laser scanner using an optical fiber in laser input conduit 36, where the output is fed as a free beam (no longer in the fiber) to a gradient index collimating lens 32 and compact plano-convex focusing lens 34 assembly. be done. This free, focused beam then rotates the two active mirrors 28 and 30 using a crank-slider transmission to direct linear actuator motion from the actuation subsystem 50 (FIG. 10) to the desired rotation. Maneuvered by transforming it into motion. Scan frame 40 (including rigid disk platform 92 slidably mounted on rigid rods 94) provides mechanical ground for actuators 18 and 22 and transmission 38, as well as optical subsystem 48 (FIG. 9) and mirrors. Ensures accurate alignment between subsystems 52 (FIG. 11).

As shown in FIGS. 4-7, the end effector 10 has two actuators 18 and 22 in the form of piezoelectric bimorph cantilevers 18 and 22, as described in US Pat. No. 9,038,942 B2 (Harvard). can contain.

The piezoelectric bimorph cantilevers 18 and 22 are smart, as described in R. Wood, "The First Takeoff of a Biologically Inspired At-Scale Robotic Insect," IEEE Transactions on Robotics, 24(2), 341 (2008). It can be manufactured via composite microstructure fabrication techniques. First, individual thin layers (eg, PbZrTiO ₃ (PZT)-5H piezoelectric layer and M60J carbon fiber/cyanate ester resin prepreg layer) are laser micromachined into the desired link shape. These layers are then stacked and aligned and subjected to a controlled cure cycle that regulates temperature, pressure, and cure time. The resulting actuators 18 and 22 are each fixed proximally to the frame 40 (including a plurality of rigid plates 92 attached along a plurality of rigid rods 94) and distally to the passive transmission linkage 38, This passive linkage 38 provides a transfer structure for translating the bending displacement of the cantilever actuator 18/22 to adjust the tilt of one of the active mirrors 28/30 to direct the reflection of the laser to the desired target. A voltage source is also coupled to the actuators 18/22 such that application of a voltage to either of the piezoelectric layers causes the actuators 18/22 to bend.

The coupling of one of the way transfer linkages 38 and one of the active mirrors 28/30 is shown in FIG. The mirror 28/30 is mounted for rotation about a pivot pin 44 attached to a rigid mount extending from a mechanical ground plate 54 in the frame and through displacement of a passive linkage 38 to pivot pin 44 in the rigid mount. rotation causes a change in the tilt angle of the active mirror 28/30.

Design requirements are derived from the envisaged surgical environment. A target field of view of 10×20 mm is selected according to the nominal size of the vocal cords. The upper diameter limit of the apparatus was chosen to be 13 mm to allow room for retraction tools, visualization, and illumination. A standoff distance of 20 mm was chosen to balance the needs of visualization and tissue manipulation while minimizing the angle of view of the scanning system. Finally, we chose a target spot size of 250 μm and a target surface velocity of 100 mm/s, according to the scanning system used in the TLM.

A variety of lasers are used in laryngeal surgery, including _CO2 , potassium titanyl phosphate (KTP), and diode lasers. _CO2 lasers are the preferred choice in many situations, but optical fibers that transmit this wavelength at high power tend to have large core diameters, which results in spot sizes that exceed design requirements. Therefore, Nufern Inc. 35 μm core PM780-HP fiber was used to design a prototype for use with a diode laser capable of transmitting at high power (60 W). However, in this prototype, a low-power fiber optic inspection laser was used to verify the mechanism. A collimator with a focal length of 6.17 mm and a condenser lens with a focal length of 38.1 mm were selected, and it was assumed that a spot diameter of 210 µm was obtained when combined with an optical fiber with a core diameter of 35 µm and a numerical aperture of 0.12. Both lenses are aspheric plano-convex to reduce aberrations. Mirror sizes of 2×2 mm and 2×5 mm with an initial angle of 40° were selected according to the kinematic analysis described below. We chose to use an off-the-shelf, factory-adjusted fiber-coupled collimator (Thorlabs F110FC-633) for simplicity of integration, although the size of the device increased.

Actuator lengths of 10.6 mm and 12.1 mm were chosen to achieve adequate displacement without significantly lengthening the device. We assume that the transmission stiffness is approximately equal to the actuator output stiffness, which means that the actuator deflection is reduced to one-half the free deflection. Under this assumption, the actuator deflections at 200 V (the upper limit of the operating voltage to avoid damage to the piezoceramic actuator material) are ±200 μm and ±220 μm, respectively.

ここで、θ_０はクランクスライダの初期角度、Δ_ｘはアクチュエータの撓み量、ｘ_０はスライダとピボット間の初期距離である。初期角度θ_０は、第１のミラーでは７０°、第２のミラーでは７５°である。２つのリンクのうち、クランクアームの長さが出力運動に最も影響を与え、それが小さいほど出力運動が大きくなるため伝達比が大きくなる。また、機構の初期角度も重要であり、これは対称性と出力振幅をトレードオフするものである。我々は非対称性を最小限に抑えながら、目的の可動範囲を実現したリンケージ構成を選択した。製作したリンケージを図１３および１４に示す。 Using the above optical model and considering the placement of the mirrors to minimize the diameter of the device, an advantageous range of motion is ±10° for the first mirror and ±15° for the second mirror. I decided. To produce these movements, the link lengths of the crank slider shown in FIG. is 0.9 mm for the first mirror and 0.6 mm for the second mirror).

where θ ₀ is the initial angle of the crank slider, Δ _x is the deflection of the actuator, and x ₀ is the initial distance between the slider and pivot. The initial angle θ ₀ is 70° for the first mirror and 75° for the second mirror. Of the two links, the length of the crank arm has the most effect on the output motion, and the smaller it is, the greater the output motion and thus the greater the transmission ratio. Also important is the initial angle of the mechanism, which trades off symmetry and output amplitude. We chose a linkage configuration that achieved the desired range of motion while minimizing asymmetry. The fabricated linkage is shown in FIGS. 13 and 14. FIG.

で表される。ｉ番目のフレームに関して点ｐ_ｊから点ｐ_ｋに向かう単位ベクトルは、

で表される。ｉ番目の座標系に対するｊ番目の座標系の方向。ｉ軸を中心とした角度θの基本回転。Ｈ_ｙはｙ軸を中心としたハウスホルダ変換である。 Given the mirror angle determined by the crank-to-slider relationship, expressed in Equation 1, the position of the laser spot on the target plane can be determined using the vector formulation of specular reflection. The symbols and geometric definitions used are given in the system schematic diagram shown in FIG. there is The j-th basis vector of the i-th coordinate system is

is represented by The unit vector from point pj to point _pk for the _i -th frame is

is represented by Orientation of the j-th coordinate system relative to the i-th coordinate system. A fundamental rotation of angle θ about the i-axis. H _y is the Householder transform about the y-axis.

ここで、θ_１，０は第１のミラーの初期方向を示す設計変数である。ここで、第１のミラー２８から反射されたビーム４６は、以下の方向を有する：

そして、ビーム４６は、以下の式で表される距離ｄ_１２を経た後に第２のミラー３０と交差する。

したがって、第２のミラー３０上のレーザビーム４６の位置ｐ_２は、以下の式によって与えられる。

同様に、第２のミラー３０からの反射ビーム４６は、以下の方向となり：

以下の距離ｄ_２ｔ後にターゲット平面５８と交差する。

最終的に、ターゲット平面上のレーザスポットの位置ｐ_ｔは次の式で求められる：

The orientation of the mirror in 3D space is given by the following equation.

where θ _1,0 is a design variable indicating the initial orientation of the first mirror. The beam 46 reflected from the first mirror 28 now has the following directions:

Beam 46 then intersects second mirror 30 after _traversing a distance d12 given by the following equation.

Therefore, the position p2 of the laser beam 46 on the _second mirror 30 is given by the following equation.

Similarly, the reflected beam 46 from the second mirror 30 will be in the following directions:

It intersects the target plane 58 after a distance d _2t of:

Finally, the position _pt of the laser spot on the target plane is given by:

The manufacturing process used to manufacture the transmission linkage follows the approach developed in P. S. Sreetharan et al., "Monolithic fabrication of millimeter-scale machines", Journal of Micromechanics and Microengineering, Vol. 22, No. 5, 055027 (2012). based and shown in Figures 16-21. Individual layers of rigid material 60 (e.g. steel), softer material 62 (e.g. polyimide), and adhesive 64 (e.g. acrylic adhesive) are processed by a 7 W, 355 nm DPSS laser micromachining system (Oxford laser E series), then aligned and set in a heated press (the bottom plate 66 of which is shown in FIG. 17) to bond layers 60, 62, and 64 together. The bonded laminate is removed from the press and a preliminary release cut is made as shown in FIG. The laminations are then bent into their desired configuration as shown in FIG. The first mirror transmission part is bent to the correct angle with the use of an assembly jig 70, as shown in FIG. 20, and the second mirror utilizes alignment pins used for lamination. Cyanoacrylate (CA) adhesive is then used to lock the laminate in an aligned configuration and a final cut is made to release the desired degrees of freedom. Each linkage 38 is placed under a confocal microscope and its functional dimensions are measured to verify the process. The manufacture of linkages 38 was a highly reproducible process with standard deviations of less than 4% of the desired value for all 12 linkages constructed, which corresponds to a 5% variation in linkage transmissibility. . The laminated transfer linkage 38 will flex (near pivot) in the longitudinal gaps between the rigid links where the flexible material is exposed.

The short link length of the crank slider makes it difficult to assemble, but by bending the physical arm backwards to create a virtual link (as shown in Figures 13 and 14), handling is greatly facilitated. Furthermore, using this approach, the bending angle of the flexure is zero at rest and stays within the elastic deformation region.

The ground connection of the linkage is attached to a 7075 aluminum alloy base structure fabricated on a 5-axis CNC machine (Bridgeport, Hardinge, Inc.). The mirror was prepared by laser cutting a 100 μm thick fused silica wafer (manufactured by Denton Vacuum Desktop Pro) on which aluminum was sputtered. A protective gel layer was added over the mirror to protect the reflective coating during assembly. The linkages were then attached to their respective actuators, inserted into the mechanical structure, and secured in place with alignment pins and press-fit plates. The actuator base and transmission ground linkage were then glued to the mechanical structure with cyanoacrylate glue. Finally, the protective gel layer was removed from the mirror by extension to complete the fabrication.

To verify the motion model of the crank slider (equation 1), the mirror angle and actuator displacement were measured as functions of the actuator voltage. Mirror angles were measured with a static voltage input using a high magnification inspection camera (Pixelink PL-B741F from Pixelink) and actuator displacement was measured at 1 Hz using a laser Doppler vibrometer (PSV-500 vibrometer from Polytec GMBH). Measured with a quasi-static cycle input. In FIG. 22, the measured 28″/30″ and predicted 28′/30″ mirror angles are plotted as a function of actuator input, along with theoretical values derived from measured actuator displacements at specific voltages. there is The results show that the model successfully captures a wide range of linkage behavior. The average absolute error of the measured data was 0.6° and 1.2° for the first mirror 28″ and the second mirror 30″, respectively.

A frequency analysis was performed on both the motion actuator-transmission-mirror subsystems to find a safe boundary for the input drive frequency. Data were collected under low voltage, white noise input using the same laser Doppler vibrometer. The results are shown in FIG. As expected, both subsystems approximate second order linear systems. The resonance frequencies are 850Hz and 750Hz, which is consistent with physical intuition. The free beam resonance (1.6 kHz) of the actuator is reduced due to the increased mass of the transmission section.

A calibrated high-speed camera (PHANTOM V710 camera from Vision Research, Inc.) with a 200 mm macro lens and two non-flickering floodlights, all mounted on an optical table, was incorporated to verify the beam-steering capabilities of the device. A benchtop scanning arena was created. The camera view is shown in Figure 24 along with the grid 75 used to align the images. One pixel corresponds to 50 μm in the image plane. The device was fixed to the optical table with a defined standoff distance of 20 mm from the target.

The scanner was then calibrated by sweeping the voltage space and tracking the position of the laser spot. The overall achieved field of view 74 is in good agreement with the model prediction 72, as shown in FIG. However, the system's unmodeled compliance and assembly inconsistency resulted in a slight warp in the laser task space. We chose to use a look-up table approach to control the position of the laser spot, rather than adding degrees of freedom to the model and calibrating it.

This approach yields reasonable results in task-space-trajectory tracking as shown in FIG. 25, where the desired trajectory is shown by plot 76. FIG. Three shapes, "H" (left), "star" (middle) and Lissajous figure (right), were drawn at different speeds (100 mm/s indicated by plot 78, 1 m/s indicated by plot 80, 2 m /s is shown in plot 82, 3 m/s in plot 84 and 7 m/s in plot 86). Each profile is shown at a base velocity of 100 mm/s (78), the highest velocity that can be reproduced before transmission vibrations impair the tracking performance of the device. Such oscillations are visible at 2 m/s of the "H" trajectory (plot 82). Of the three shapes, "H" is the most difficult shape because the trajectory changes abruptly. The Lissajous figure is the simplest with little performance degradation up to 7 m/s (plot 86) because the actuator drive voltage is smooth and nearly sinusoidal.

This prototype device meets most of the design requirements of field of view (slightly smaller than 10×20 mm), scanning speed (up to 7 m/s), and scanner size (11 mm). The combination of assembly misalignment and unmodeled off-axis compliance causes errors in the model of laser spot position, as shown by the resulting field distortion in FIG. This can be improved by minimizing the amount of manual manipulation required for assembly and using other bending materials or geometries with better compliance ratios.

Calibration and feedforward control allow qualitative trajectory tracking, but because calibration is performed statically and does not capture dynamic, nonlinear, or hysteresis effects, significant deviations from the desired trajectory remain. Therefore, feedback control may be necessary to precisely control the position of the laser spot. As such, embodiments of the apparatus may incorporate angle detection at the mirror output or a means of direct feedback of the laser position to the controller.

Another important next step is the integration of high power optics. To that end, higher quality mirror coatings can be incorporated. Among the available mirror coatings, gold is a favorable option due to its high reflectivity (>97%) at favorable wavelengths of 800-1000 nm. Dielectric coatings are also worthy of consideration as they reach up to 99.8% reflectance, but are more selective with respect to wavelength.

Because the mechanical structure of the mirror and linkage is rather fragile, they can be enclosed to protect them, protecting the mirror from fluid flow at the surgical site. The device can be used with existing transoral robotic tools for visualization and tissue retraction, thus coordinating these tools and tasks.

In various embodiments, a gradient index collimating lens collects light from a ferrule-terminated optical fiber and directs it to a compact plano-convex focusing lens. The light is reflected by a 45° incident angle mirror and enters a small two-mirror galvanometer. A flexible linkage converts the quasi-linear motion of the piezoelectric bending actuator into rotational motion of the galvanometer mirror. Cylindrical profile facilitates integration with existing surgical instruments.

The following are the design, manufacturing, and control considerations that are perfected by this laser steering solution. First, general design considerations for miniaturizing the galvanometer portion of the device are discussed. This part is the easiest part to miniaturize from both a design and manufacturing standpoint. Details of the design and construction of each part and their assembly are given below. Third, we report the methods used for static position control and characterization. Finally, the dynamic properties of the device, demonstration of high-bandwidth operation, and interfacing the device with commercial colonoscopes are described.

Although the galvanometer is the most complicated part of the device to miniaturize in design, there are some general insights that guide our approach regarding the design space. The objective is to minimize the distance between the mirrors, given the beam size, mirror size, and desired range of motion, while avoiding collisions between the mirrors and between the reflected beam and the previous mirror in the optical path. (see FIGS. 26-28). An important high level design consideration is the number of mirrors used. Counter-intuitively, a three-mirror design can actually be smaller than a two-mirror design if the same range of motion is required for each.

First, consider the three mirror designs shown in the three configurations of FIG. The incident beam enters from the left and is then reflected in turn by fixed mirror 42, first active mirror 28 and second active mirror 30 (4 mm circumscribed diameter). In the left figure, the first and second active mirrors 28 and 30 are rotated +10°. In the middle figure, the first active mirror 28 is rotated +10° and the second active mirror 30 is rotated -10°. In the right figure, the first active mirror 28 is rotated -10° and the second active mirror 30 is rotated +10°. If the distance between the fixed mirror 42 and the first active mirror 28 is too small, the reflected light from the second active mirror 30 will cross the fixed mirror 42 . If the distance between the first active mirror 28 and the second active mirror 30 is too small, they will collide. However, increasing the distance between the mirrors not only increases the size of the device, but also means that a larger area mirror is required to collect the reflected light over the same range of motion. The illustrated three-mirror design balances all of these considerations, resulting in a device with a 4 mm diameter footprint and a ±10° range of motion for each active mirror. Note also that chamfering the corners of the mirrors prevents collisions in critical places and increases the range of motion.

The first two-mirror design (shown in two configurations in FIG. 27) has the same diameter footprint as the three-mirror design, but its range of motion is halved along the first mirror axis. In the left image, the first active mirror 28 is rotated at an angle of +5°, while the second active mirror 30 with a 4 mm circumscribed diameter is at a neutral 0° angle. In the right image, the first active mirror 28 is rotated -5° and the second active mirror 30 is at a neutral 0° angle. The result of a series of trade-offs is that if mirrors 28 and 30 (both active) are too close together, the beam reflected from the second active mirror 30 will be intersects the first active mirror 28 at . On the other hand, if the distance between the two mirrors 28 and 30 is increased, for large negative rotation angles of the first mirror 28, the second mirror 30 must be increased to accept the incident light. This is the second two-mirror design (FIG. 28). It achieves the same range of motion as the 3-mirror design at the expense of a 50% increase in diameter (the circumscribed diameter of the second mirror 30 is 6 mm). In the left image, the first active mirror 28 is rotated +10° and the second active mirror 30 is at a neutral 0° angle. In the right image, the first active mirror 28 is rotated -10° and the second active mirror 30 is rotated +8°.

Thus, a three-mirror galvanometer (Fig. 26) achieves a wider range of motion than a two-mirror design of the same size (Fig. 27), which in turn achieves the same range of motion as a three-mirror design. requires a 50% larger diameter. The range of motion is determined primarily by the ability of the mirrors to fully capture and reflect incident light, but is limited by the need to avoid collisions between mirrors and the reflected laser with the mirrors ahead of it in the optical path. . These sample configurations show the limits of the range of motion where these collisions are likely to occur.

A fixed beam diameter of 1 mm was assumed throughout this analysis. This is slightly higher than the low power pointing laser used to validate the device, but is a reasonable upper limit for a collimated high power beam. For simplicity, the neutral position of each mirror is chosen to be at a 45° angle of incidence with the input beam, and slight deviations from 45° may result in slightly different results, but the design trade-off structure is I made sure it didn't change. We also assumed that a symmetrical range of motion was desirable. Again, otherwise the resulting design may vary slightly, but the nature of the design space need not change. Finally, it is emphasized that we are considering the case where the outgoing rays are parallel to the incoming fiber (forward looking). If we want the output ray to be perpendicular to the input fiber (side view), there is no reason to use the 3-mirror design, and the 2-mirror design is perfectly acceptable in terms of compactness and range of motion. However, since most energy delivery tools used in surgery are forward looking, we have chosen to use this configuration for this device example, while other examples of devices simply employ side viewing devices. be able to.

Armed with these overall insights, the detailed design and fabrication of the device is carried out. Fabrication uses a mix of off-the-shelf and custom parts made primarily by laser micromachining (using an Oxford Laser E-series with a Coherent Avia 355-7 laser and a Canon galvanometer). The kinematic structure of the three-mirror galvanometer piezoelectric bending actuator motion transmission assembly is shown in FIGS. This assembly converts quasi-linear (parabolic) input motion into rotational motion of the mirror.

The components of the 3-mirror galvanometer before assembly are shown in FIG. 31 (in assembly order, left to right in the first row, then left to right in the second row). The components shown are a retaining clip 88, a fixed mirror 42 assembly, a second active mirror (y-axis) 30 assembly, a first active mirror (x-axis) 28 assembly, a focusing lens 34 assembly, a piezoelectric It comprises the actuators 18 and 22 assemblies, the collimating lens 32 assembly and the support superstructure 90 . Retaining clips, mirrors 42, 28, 30, lenses 34, 32, and actuators 18, 22 are each mounted on a disk platform 92 having an orifice through which platform 92 is slidably attached to rod 94 of support superstructure 90. , thereby providing a detachable modular structure. These components can be formed by UV laser cutting. The active mirrors 28, 30 assembly and the piezoelectric actuators 18, 22 assembly may comprise precision laminations. Sputter deposition may be used to form the mirrors 28, 30, 42 assembly. The lenses 32 and 34 can be off-the-shelf parts. Finally, diamond grinding can be used to shape the focusing lens 34 .

Specific details of the design, manufacture and function of the components are provided below.

Steel rod superstructure 90: This component consists of two 500 μm and one 300 μm diameter stainless steel rods 94 (Misumi, USA) on which the rest of the components are assembled. Rods 94 are positioned orthogonally to FR4 disk 92 using an alignment jig. A spring steel preload spring is attached to the disk 92 to compress and hold the assembled parts in place. All components are laser micromachined.

Ferrule fiber and collimating lens 32: A commercially available ferrule-terminated optical fiber (SMPF0106-FC, Thor Labs) was assembled with a gradient index collimator 32 (GRIN2306A, Thor Labs) and attached to the FR4 support disk 92.

Piezoelectric bending actuators 18, 22: N. T. Jafferis, M. J. Smith, R. J. Wood, "Design and manufacturing rules for maximizing the performance of polycrystalline piezoelectric bending actuators", Smart Materials and Structures, Vol. 24, No. 6, p. 065023 (2015 ) were used to fabricate actuators 18 and 22 to size. Due to the available space next to the optics, the dimensions of the actuator were chosen with an effective length of 7 mm, a tip length of 1.8 mm, a bridge length of 0.5 mm, a base width of 1.4 mm and a tip width of 0.4 mm.

The actuators are driven in a unipolar configuration biased at a fixed bias voltage, so each is controlled by a single time-varying input signal from zero to the bias voltage. A fixed bias voltage of 200 V was chosen to achieve appreciable output displacement while ensuring that the tensile strain of the piezoceramic was well below the failure limit. Under these driving conditions, the actuator achieved a free displacement of ±200 μm and had an initial resonant frequency of 2.6 kHz.

Focusing lens 34: Focusing lens 34 was obtained off-the-shelf (#89-003, Edmund Optics) and ground down in size using an alignment jig and a diamond cutoff wheel. Laser pre-engraved register marks on the lens 34 allow alignment of the optical center after grinding.

Articulating mirrors 28, 30 and motion transmitters: These are complex assemblies of rigid and non-rigid parts manufactured using lamination techniques. These may include a 4-bar crank-slider linkage formed from stainless steel, polyimide, and a thermoset acrylic adhesive (PYRALUX adhesive from Dupont Inc). The mirrors 28, 30 are positioned on cranks and the sliders each interface with one of the piezoceramic actuators 18/22. The x-axis (first) transmission further includes a linearizing linkage to compensate for out-of-plane motion of the bending actuator tip. These are shown schematically in FIGS. Mirrors 28, 30 are made from sputtered aluminum (Denton Depcale Pro PVD Systems, Denton Vacuum LLC, Moorestown, NJ, USA) on a 100 μm fused silica substrate and singulated using a UV laser. .

The detailed design of the transmission part is based on the properties of the actuator. Similar to state-of-the-art devices, we wanted to achieve ±10° of motion for each mirror (driven by bending the actuators in either direction). There are two important design considerations in achieving this motion: (1) linkage transmission ratio and (2) linkage stiffness relative to actuator stiffness. A target transmission ratio of 0.1°/μm and a target stiffness equivalent to the actuator were selected based on experience with sizing similar mechanical components. The device achieved transmission ratios of 0.13°/μm and 0.12°/μm (due to small manufacturing tolerances) and stiffness of 60% and 90% of the actuator stiffness.

Note that the stiffness of the transmission is parallel to the stiffness of the actuator, resulting in a reduced free displacement of the actuator. Two mirrors fabricated in this way realized a movable range of -12.5 to 20° and -11.2 to 13.7°, respectively. This asymmetry corresponds to slight assembly misalignment and slightly non-linear transfer kinematics. A neutral (zero) mirror angle and actuator position corresponds to a configuration in which the output beam is aligned along the longitudinal axis of the device.

Fixed Mirror 42 : This aluminum sputtered fused silica mirror 42 is fixed at 45° to the incident light using two alignment blocks and interfaces with the FR4 support disk 92 .

Retaining clip 88 : This spring steel piece fits into a groove cut into the stainless steel rod 94 of the superstructure 90 . This axially constrains the assembly in conjunction with preload springs located on the superstructure base.

Spacer Tubes and Disks: Parts that are laser micromachined to ensure proper spacing and alignment between parts. These are the dimensions where length (or thickness) is important.

We began to characterize end effector position control by measuring open loop repeatability. This is an important indicator of the fundamental limits of the physical properties of the device to reproduce the same motion. Phenomena such as stiction and plasticity mean that identical inputs do not produce identical outputs. One-way reproducibility is a measure of reproducibility approaching the measurement point from only one direction. The maximum 2σ standard distance of the sampled points is 200 μm, which means that there is 95% confidence that a series of identical motions will be within a radius of variance of 200 μm with respect to the mean trajectory.

The presence of hysteresis complicates position control. Hysteresis is a bi-directional effect that arises primarily from domain reorientation within the piezoceramic actuator, meaning that the laser position depends on the time history of the input. This dependency is clearly undesirable as it complicates control and makes use of the device non-intuitive. A feedforward correction scheme was introduced to minimize this hysteresis effect. To test this approach, star trajectories were commanded for uncorrected and corrected inputs. Raw inputs clearly show path-dependent effects, whereas corrected inputs show significantly improved tracking. This is essentially a two-way reproducibility measure. Quantitatively, the maximum 2σ standard distance around the setpoint is 2.14 mm without correction and 0.72 mm with correction, which represents a reasonable improvement in feedforward correction. Further improvements can be achieved with feedback control.

Due to the low dimensionality of the workspace and input space and lack of sensor information, using model-free direct mapping between actuator input and laser spot position, cascaded with hysteresis feedforward correction You have chosen to control the device. Third and second order polynomial surfaces were fitted to the open-loop repeatability measurement data for the first and second mirrors, respectively. These fits were centered at 73V and 93V, respectively, corresponding to the neutral angles of the mirrors.

The system can be dynamically controlled and characterized. The bandwidth of the system is limited by mirror resonances at high frequencies. The two mirror primary The resonant frequencies are 1.8 kHz and 1.9 kHz. Additionally, there is a low frequency mode at 1.2 kHz in the first mirror (probably due to twist and other off-axis modes). To avoid the occurrence of these modes, a finite jerk motion profiling scheme (also called sigmoid or S-profiling) is used.

The system exhibits only minor deviations from the static trajectory 26 at high speeds, as seen in FIGS. There is only a 5% deviation between the trajectories followed at low speed (7.8 mm/s, solid plot in FIG. 35) and high speed (3,900 mm/s, dashed plot in FIG. 35). Two-axis control also allows the system to trace complex planar trajectories. The wide bandwidth of the system can also be used to generate multimodal profiles. These are trajectories in which high-frequency input is superimposed on low-frequency input, allowing the user to change the effective area of energy application on the fly, thus controllably covering large areas, such as large area hemostasis. It is especially effective in situations where it is necessary.

The low profile and low mass (eg, 700 mg) of the laser steering end effector allows it to be easily interfaced with existing surgical instruments. To demonstrate this, it was attached to the end of a colonoscope (Olympus CF-100L) and simulated polypectomy tasks were performed on a benchtop surgical simulator. Both remote control using a standard input device (Phantom Omni) and fast robotic control of the laser along the registered cutting trajectory are shown.

This research points the way to new ways to control energy delivery in minimally invasive surgery. This is due to (1) giving the surgeon greater control over soft tissue energy delivery, (2) improving the maneuverability and dexterity of surgical instruments, and (3) physical strain on both the operator and the subject. It can simultaneously address three key challenges in surgical technology: reducing . This contribution allows the operator to control the laser velocity as it interacts with the tissue, thus making it possible to adjust and optimize the quality of the laser-tissue interaction more broadly than existing statically used tools. make it possible to Using a wrist-type joint, the operator can now access previously inaccessible lesions. Our design, fabrication, and modular assembly approach are additional contributions that enable the creation of this device, but are also adaptable to other complex microrobotic systems and medical devices.

Sensory feedback can be incorporated to achieve accuracy in line with device reproducibility. A simple approach is to embed a strain gauge sensor within a piezoelectric bending actuator to estimate the position of the actuator and use current sensing to estimate the velocity of the actuator. The mirror position can then be calculated from the transfer kinematics and the laser position estimated from the specular reflection model. Direct measurement of the mirror position provides a more accurate estimate of the laser position, but the path to a suitable fine sensing method is not as straightforward as sensing actuator movement. Visual feedback can also be used to make high quality estimates, albeit at a lower sample rate than electromechanical sensors. In practice, sensor fusion, which fuses these various pieces of information, seems to be the best approach.

Additionally, incorporating appropriate high power fibers, lenses, and mirrors, the device can be used with surgical lasers. Component selection depends on the wavelength and power of the laser used. For example, when using a _CO2 surgical laser, gold-sputtered aluminum mirrors and zinc selenide lenses provide adequate reflectance and transmittance, respectively. In particular, attention is paid to the "laser-induced damage threshold," which is a measure of the laser power that an optical component can receive before it degrades.

Regardless of the laser modality used, the device can be advantageously encapsulated to be robust against fluids and debris within the surgical environment and sterilizable. Since the tip of the laser fiber can become damaged after prolonged use, it can be advantageous to incorporate a method of disconnecting the laser fiber from the device. This severing function allows the laser fibers to be individually cleaned and cleaved, greatly extending the life of the laser fibers.

Because the position of the laser is electronically controlled rather than cable-actuated, energy control can be decoupled from the overall movement of the surgical instrument in which the laser is located. This independence provides flexibility that often requires tedious manual tasks such as device handoff, endoscope placement, multiple hand movements to various parts of the instrument, and end effector manipulation by another user. This is of particular importance for endoscopic examinations. Therefore, with a remote control column such as a joystick, it can be ergonomically mounted anywhere on the endoscope or mounted on a second operator remote from the endoscope as it is not position dependent due to space constraints of the cable. It can be easily imagined to improve the efficient use of time in the operating room, which is used for patient care rather than for equipment operation.

Our laser steering approach also enables new approaches for endoscopic visualization and visual biopsy. Optical coherence tomography and confocal endoscopy use laser/tissue interactions to visualize subsurface structures, allowing scanning to see large areas of tissue at once. Optical steering can also be used to extend the effective field of view of standard white-light imaging tools by stitching together a series of images acquired in fast scans. The scanning systems and modular device assembly approaches described herein can be adapted for manufacturing millimeter-sized versions of those systems. Smaller versions of these systems are built using stack fabrication techniques that use electrostatic and electrothermal actuators to excite resonant scanning elements. Our approach has the advantages of simple structure and quasi-static wide range of motion.

The technology is also expected to be applied to other microrobot systems, especially small aircraft and satellites where size and weight are important. This technology enables the production of miniature light detection and ranging (LIDAR) sensors used for mapping and navigation, and laser scanners used for wide-area air pollution detection.

Additional examples consistent with this teaching are provided in the following numbered items.

1. A miniature laser steering end effector comprising:
a frame having a proximal end and a distal end and having a maximum dimension in a plane orthogonal to the longitudinal axis of 13 mm or less;
at least two mirrors mounted proximate a distal end of the frame and including a first active mirror and a second active mirror;
a first actuator attached to the frame and configured to change the tilt of the first active mirror with respect to the frame;
a second actuator attached to the frame and configured to change the tilt of the second active mirror with respect to the frame;
A path is provided for delivering a laser beam through the frame to the mirrors, the mirrors being positioned and configurable via the actuators to reflect the laser beam at each mirror toward an external target. A miniature laser steering end effector, comprising:
2. The miniature laser steering end effector of Claim 1, further comprising a third mirror arranged and configured to reflect said laser beam with said first and second active mirrors.
3. 3. The compact laser steering end effector of item 2, wherein the third mirror is fixedly mounted.
4. A miniature laser steering end effector according to items 1-3, wherein the first and second actuators are cantilevers.
5. 5. The miniature laser steering end effector of item 4, wherein the cantilever is coupled with a mirror via a passive linkage.
6. 6. A miniature laser steering end effector according to item 4 or 5, wherein the cantilever is a bimorph piezoelectric cantilever.
7. The miniature laser steering end of paragraphs 1-6, further comprising a surgical laser positioned to direct a laser beam through the miniature laser steering end effector and onto the mirror for steering via reflection from the mirror. effector.
8. 8. The miniature laser steering end effector of clause 7, further comprising a navigate laser arranged to direct a laser beam through the miniature laser steering end effector onto a mirror for steering via reflection from the mirror.
8.1 The miniature laser of item 1, wherein said frame comprises a plurality of rods and a plurality of platforms attached to said rods, said platforms mounting components of said miniature laser steering end effector. steering end effector.
9. A robotic laser steering method comprising:
generating a laser beam;
directing the laser beam into a proximal end of an end effector and toward a region near the distal end of the end effector;
reflecting a laser beam off at least two active mirrors in a region near the distal end of the end effector;
using an actuator to change the tilted orientation of the at least two active mirrors to move the laser beam across the target;
method including.
10. 10. The method of item 9, further comprising displacing the laser beam with a third mirror in combination with the at least two active mirrors.
11. 11. Method according to item 10, wherein the third mirror is fixedly mounted.
12. Method according to items 9-11, wherein the actuator is a cantilever.
13. 13. The method of item 12, wherein bending the cantilever displaces a passive linkage coupled to the mirror to change the tilt of the mirror.
14. 14. The method of items 9-13, wherein the target is an organism.
15. 15. The method of item 14, wherein said organism is a human.
16. Ablation of benign or cancerous lesions of the pharynx and larynx, or laser-assisted cardiac ablation, gastrointestinal laser-assisted surgery, laser-assisted abdominal surgery, or laser-assisted transnasal surgery in the human body via displacement of the laser beam by said mirrors 16. The method of item 15, further comprising performing skull base surgery in situ.

In describing embodiments of the present invention, specific terminology is used for the sake of clarity. For purposes of description, specific terms are intended to include technical and functional permeants that operate in a similar manner to achieve at least similar results. Further, in some instances where certain embodiments of the invention include multiple system elements or method steps, those elements or steps may be replaced with a single element or step. Similarly, single elements or steps may be replaced with multiple elements or steps serving the same purpose. Further, when parameters of various properties or other values are specified herein for embodiments of the present invention, those parameters or values are 1/100, 1/50, 1/ 20, 1/10, 1/5, 1/3, 1/2, 2/3, 3/4, 4/5, 9/10, 19/20, 49/50, 99/100, etc. (or can be multiplied by 1, 2, 3, 4, 5, 6, 8, 10, 20, 50, 100, etc.), or rounded approximations thereof, or variation of any of the above for a specified parameter (eg, if the specified parameter is 100 and the variation is 1/100, the value of the parameter is in the range of 0.99 to 1.01). Moreover, although the present invention has been shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that various substitutions and changes in form and detail may be made without departing from the scope of the invention. would do. Moreover, other aspects, features, and advantages are also within the scope of the invention, and not all embodiments of the invention need necessarily achieve all the advantages or have all the features described above. Moreover, steps, elements, and features discussed herein in connection with one embodiment can be used in combination with other embodiments as well. The contents of the references, including references, journal articles, patents, patent applications, etc., cited throughout the text are hereby incorporated by reference in their entirety for all purposes. And all appropriate combinations of the embodiments, features, characteristics, and methods from these references and this disclosure can be included in embodiments of the invention. In addition, the components and steps identified in the background section are essential to this disclosure and within the scope of the invention may be combined with or in place of components and steps described elsewhere in this disclosure. can be used. In a method claim (or where the method is cited elsewhere), if the steps are recited in a particular order (with or without order letters added for ease of reference), especially The steps are not to be construed as limited to their order in time unless explicitly stated or implied by the terms and expressions.

Claims (17)

A miniature laser steering end effector comprising:
a frame having a proximal end and a distal end and having a maximum dimension in a plane orthogonal to the longitudinal axis of 13 mm or less;
at least two mirrors mounted proximate a distal end of the frame and including a first active mirror and a second active mirror;
a first actuator attached to the frame and configured to change the tilt of the first active mirror with respect to the frame;
a second actuator attached to the frame and configured to change the tilt of the second active mirror with respect to the frame;
A path is provided for delivering a laser beam through the frame to the mirrors, the mirrors being positioned and configurable via the actuators to reflect the laser beam at each mirror toward an external target. A miniature laser steering end effector, comprising: 2. The miniature laser steering end effector of claim 1, further comprising a third mirror positioned and configured to reflect said laser beam with said first and second active mirrors. 3. The miniature laser steering end effector of claim 2, wherein said third mirror is fixedly mounted. 2. The miniature laser steering end effector of claim 1, wherein said first and second actuators are cantilevers. 5. The miniature laser steering end effector of claim 4, wherein the cantilever is coupled with a mirror via passive linkage. 5. The miniature laser steering end effector of claim 4, wherein said cantilever is a bimorph piezoelectric cantilever. The miniature laser steering end effector of claim 1, further comprising a surgical laser positioned to direct a laser beam through the miniature laser steering end effector onto a mirror for steering via reflection from the mirror. . 8. The miniature laser steering end effector of claim 7, further comprising a navigate laser positioned to direct a laser beam through the miniature laser steering end effector onto a mirror for steering via reflection from the mirror. . 2. The miniature laser steering end of claim 1, wherein the frame comprises a plurality of rods and a plurality of platforms attached to the rods, the platforms mounting components of the miniature laser steering end effector. effector. A robotic laser steering method comprising:
generating a laser beam;
directing the laser beam into a proximal end of an end effector and toward a region near the distal end of the end effector;
reflecting a laser beam off at least two active mirrors in a region near the distal end of the end effector;
using an actuator to change the tilted orientation of the at least two active mirrors to move the laser beam across the target;
method including. 11. The method of claim 10, further comprising displacing the laser beam with a third mirror in combination with the at least two active mirrors. 12. The method of claim 11, wherein said third mirror is fixedly mounted. 11. The method of claim 10, wherein said actuator is a cantilever. 14. The method of claim 13, wherein bending the cantilever displaces a passive linkage coupled to the mirror to change the tilt of the mirror. 11. The method of claim 10, wherein said target is a living organism. 16. The method of claim 15, wherein said organism is human. Ablation of benign or cancerous lesions of the pharynx and larynx, or laser-assisted cardiac ablation, gastrointestinal laser-assisted surgery, laser-assisted abdominal surgery, or laser-assisted transnasal surgery in the human body via displacement of the laser beam by said mirrors 17. The method of claim 16, further comprising performing skull base surgery in situ.

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